1. Field of the Invention
The present invention relates to resin compositions which exhibit wet and dry strength properties and contain no organic chlorides.
2. Description of Related Art
Polyamine-epichlorohydrin resins have been used as wet strength resins for paper since the early 1950's. Such resins are cationic and are particularly useful because they are formaldehyde-free and develop wet strength at neutral or alkaline pH values.
One of the drawbacks associated with the use of polyamine-epichlorohydrin resins is the emission of harmful chlorinated compounds into the water systems of pulp and paper mills. These chlorinated compounds, including 1,3 dichloro-2-propanol, epichlorohydrin and 1-chloro-2,3-propanediol, are usually discharged into the effluent waste water systems because they are only partially substantive to cellulose pulp fibers. The permissible amounts of these chlorinated compounds is decreasing and therefore efforts have been made to reduce the amounts of these materials.
Efforts have been made to reduce the amount of organic chloride impurities. For example, Fischer et al., U.S. Pat. No. 5,116,887; European Patent Publication No. 0 508 203; Devore et al., U.S. Pat. Nos. 5,189,142 and 5,239,047; and Fischer et al; U.S. Ser. No. 08/165,779 filed Dec. 10, 1993 disclose low chlorine component polyamine-epichlorohydrin resins produced by modifying the reaction temperature and/or the epichlorohydrin/nitrogen ratio. Nonetheless, some quantity of organic chlorides are produced necessitating expensive and time-consuming disposal.